Date: Sun, 30 Mar 2003 10:43:51 -0800 From: Wes Peters <wes@softweyr.com> To: kientzle@acm.org, "Bruce A. Mah" <bmah@FreeBSD.ORG> Cc: freebsd-hackers@FreeBSD.ORG Subject: BSD tar (was Re: Making pkg_XXX tools smarter about file types...) Message-ID: <200303301043.51087.wes@softweyr.com> In-Reply-To: <3E85418F.8010201@acm.org> References: <3E42C148.4050807@acm.org> <20030329012828.GA32891@intruder.bmah.org> <3E85418F.8010201@acm.org>
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On Friday 28 March 2003 22:47, Tim Kientzle wrote:
>
> P.S. It's galled me for a while that pkg_add has
> to fork 'tar' to extract the archive.
Me too, me too.
> I've started
> piecing together a library that reads/writes tarfiles.
Excellent. A general design goal in userland should be to implement
functionality in libraries and then wrap small driver programs around
them to export the basic functionality to userland. I guess this partly
violates the original UNIX tools philosophy, but all it really does is
move it from the original pipes interfaces into the dynamic linker.
> With this, it should be possible to make pkg_add
> considerably more efficient. In particular, rather
> than extracting to a temp directory, then parsing important
> information, then moving the files, it should be
> possible using this library to read the initial
> entries ("+CONTENTS", in particular) directly into
> memory, process the information there, then extract the
> remainder of the package files directly into their
> final locations.
I'd much rather see the metadata moved outside the file archives, but
that's a separate argument and in now way detracts from your proposed
work. ;^)
> So far, I have a library API
> outlined, and functional read support implemented.
> Next step is to hack up a minimal tar implementation
> that uses it to make sure everything's working
> correctly.
>
> So far, the library automatically detects compression
> formats (using techniques like those in my
> pkg_install patch) and has some rough support
> for detecting the archive format as well.
> (One goal of mine: support for 'pax extended
> archives', which I understand can handle ACLs.)
I have wondered outloud before if pax might be a suitable starting place
for such a hacking expedition. Others who've worked on pax assure me it
is not. ;^( Sigh. So much code, so few programmers.
> Of course, such a library could also form the
> basis for a BSD-licensed tar to replace GNU tar.
> I understand a few people have wanted such a thing.
Why yes, yes they have.
--
Where am I, and what am I doing in this handbasket?
Wes Peters wes@softweyr.com
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